Yes the Jetta diesel requires turbocharging. Pretty much all of the engine mechanical needs to be addressed to achieve respectable and reliable
horsepower output. Engine fasteners like capscrews need to be replaced with studs and nuts and not the counterfeit offshore crap either. I will
only use studs and nuts made in USA from American steel. They're the only ones that I trust in a big dollar engine and a Jetta diesel putting out
upwards of 300 to 350 horsepower is a big dollar engine.
Engine aside, have you given any consideration to what transmission would be mated to it. There are bell housing adapters available for joining
429-460 Ford engines onto GM Turbohydramatic transmissions for example. I rather have my doubts that there is a bell housing adapter in existence
for joining a Jetta diesel engine to a Chrysler Torqueflite transmission; so one would have to be created and a "one-off" certainly wouldn't be cheap.
If you are genuinely serious about proceeding with this little endeavour you might want to see if you can get yourself a nice case of diarrhea so
can start crapping out thousand dollar bills; and lots of them, cuz yer gonna need 'em.
Like I said in my previous post in which I provided links; the guy that you want to talk to about doing this is TOM CALVERT at Illinois Dyno.